The presents invention relates generally to a sander, and more particularly to a power-driven sander. Still more specifically, the invention relates to a gyratory sander which is driven by a fluid motor.
Motor-driven gyratory sanders are well known, having a housing, a drive arrangement and a sanding plate which has gyratory motion imparted to it by the drive arrangement and which carries in operation the abrasive sandpaper or the like. The known constructions of this type use an electromotor which is mounted in the housing and which drives the sanding plate via an eccentric shaft. Electromotors of the type required for such applications are relatively heavy and certainly expensive, and they are also relatively large and are not easy to accommodate in the housing if it is desired to maintain the housing small. Moreover, it is a particular disadvantage of these prior-art constructions that they require special weights to balance the gyratory mass of the plate, in order to eliminate unpleasant vibrations and difficult control over the sander.